The invention relates to the apex seals of rotary mechanisms such as rotary engines, rotary pumps or expansion engines and is particularly directed to an apex seal construction for such a mechanism, for example of the type disclosed in U.S. Pat. No. 3,400,691 or No. 3,712,767.
As disclosed in said prior patents, each apex seal consists of a main seal strip which extends substantially across the width of the engine cavity between its end walls with one or both ends of this main seal strip being cut back to form an inclined end face such that the outer edge of the strip is longer than its inner or bottom edge. A generally triangular shaped seal piece is placed at the inclined end or corner of the main seal piece to complete this corner of the apex seal. As shown in said prior patents, the main seal piece and the triangular end seal piece each have an inclined flat surface engaging an adjacent flat surface of the outer seal piece. These inclined flat engaging surfaces must be at precisely the proper angle otherwise the triangular end seal piece will be misaligned relative to and not run flat against the end wall of the adjacent side housing. In such a situation a corner of the end seal piece will run against the side housing. This may cause scuffing or grooving of the side housing and, in addition, because of said misalignment, the triangular end seal piece does not provide a good seal against the side housing thereby adversely affecting the efficiency of the rotary mechanism. It has been found that with the apex seal construction of this prior patent such misalignment of an end seal piece may result from normal manufacturing tolerances.